<style type="text/css">
    #info {
        display: block;
        position: relative;
        margin: 0px auto;
        width: 50%;
        padding: 10px;
        border: none;
        border-radius: 3px;
        font-size: 12px;
        text-align: center;
        color: #222;
        background: #fff;
    }
</style>
<div id="map"></div>
<pre id="info"></pre>
<script>
    var map = new mapboxgl.Map({
        container: 'map', // container id
        style: 'mapbox://styles/mapbox/streets-v11',
        center: [-74.5, 40], // starting position
        zoom: 9 // starting zoom
    });

    map.on('mousemove', function(e) {
        document.getElementById('info').innerHTML =
            // e.point is the x, y coordinates of the mousemove event relative
            // to the top-left corner of the map
            JSON.stringify(e.point) +
            '<br />' +
            // e.lngLat is the longitude, latitude geographical position of the event
            JSON.stringify(e.lngLat.wrap());
    });
</script>
